Efficient Sparse Network Resource Usage and Connection Release

ABSTRACT

This disclosure relates to techniques for efficient sparse network resource usage and connection release procedures. According to some embodiments, a wireless device may utilize techniques for efficiently releasing a radio resource control (RRC) connection, including techniques that avoid or reduce the occurrence of random access procedures when out-of-sync with the network when the RRC connection is being released. In some embodiments, a wireless device may utilize techniques for efficiently sparsely using network uplink resources, including techniques that avoid or reduce the occurrence of random access procedures to regain timing alignment to perform uplink communication when out-of-sync with the network.

PRIORITY INFORMATION

This application claims priority to U.S. provisional patent applicationSer. No. 62/210,250, entitled “Efficient Sparse Network Resource Usageand Connection Release,” filed Aug. 26, 2015, which is herebyincorporated by reference in its entirety as though fully and completelyset forth herein.

FIELD

The present application relates to wireless devices, including toapparatuses, systems and methods for efficient sparse network resourceusage and connection release.

DESCRIPTION OF THE RELATED ART

Wireless communication systems are rapidly growing in usage.Additionally, there exist numerous different wireless communicationtechnologies and standards. Some examples of wireless communicationstandards include GSM, UMTS (associated with, for example, WCDMA orTD-SCDMA air interfaces), LTE, LTE Advanced (LTE-A), HSPA, 3GPP2CDMA2000 (e.g., 1×RTT, 1×EV-DO, HRPD, eHRPD), IEEE 802.11 (WLAN orWi-Fi), IEEE 802.16 (WiMAX), Bluetooth, and others.

Cellular communication technologies may be capable of providing avariety of services, and may be used by a variety of applications.Different applications utilizing cellular communication may havedifferent characteristics. Cellular communication techniques which donot take into account the different application characteristics of thevarious applications utilizing cellular communication may operateinefficiently. Accordingly, improvements in the field would bedesirable.

SUMMARY

Embodiments are presented herein of apparatuses, systems, and methodsfor efficient sparse network resource usage and connection release ofwireless devices.

According to some embodiments described herein, a wireless device mayimplement techniques that avoid or reduce the need to perform randomaccess procedures when releasing a radio resource control (RRC)connection. For example, techniques are described herein for releasingthe RRC connection of a wireless device without requiring the wirelessdevice to provide any acknowledgement in response to an indication(e.g., an RRC connection release message or a specially designatedpaging message) to release the RRC connection. Techniques are alsoprovided for a wireless device to release the RRC connection withoutreceiving any indication to release the RRC connection from the network,e.g., by utilizing a local RRC connection release timer synchronizedwith a network-side RRC connection release timer. Still furthertechniques are provided for a wireless device to provide acknowledgementin response to an indication from the network to release the RRCconnection, in which the network assists the wireless device to reducethe number of random access procedures needed to complete the RRCconnection release by providing uplink resources (e.g., schedulingrequest resources, sounding reference signal resources, an uplink grant,etc.).

Additionally or alternatively, according to some embodiments describedherein, a wireless device may implement techniques that avoid or reducethe need to perform random access procedures when sparsely utilizinguplink resources. For example, techniques are described herein for awireless device to use previously received timing alignment informationto request uplink resources and perform uplink communication even afterits timing alignment timer has expired (e.g., if the wireless device hasbeen relatively stationary such that the timing alignment information isreasonably likely to still be functional). According to someembodiments, the wireless device may retain and use scheduling requestresources to request the uplink resources for the uplink communicationafter the timing alignment timer has expired, e.g., rather thanreleasing those resources upon expiration of the timing alignment timer.Additionally or alternatively, the network may (e.g., if it is expectingthe wireless device to sparsely use uplink network resources)occasionally provide uplink grants to the wireless device even afterexpiration of the timing alignment timer.

The techniques described herein may be implemented in and/or used with anumber of different types of devices, including but not limited tocellular phones, cellular base stations, tablet computers, wearablecomputing devices, portable media players, and any of various othercomputing devices.

This Summary is intended to provide a brief overview of some of thesubject matter described in this document. Accordingly, it will beappreciated that the above-described features are merely examples andshould not be construed to narrow the scope or spirit of the subjectmatter described herein in any way. Other features, aspects, andadvantages of the subject matter described herein will become apparentfrom the following Detailed Description, Figures, and Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present subject matter can be obtainedwhen the following detailed description of the embodiments is consideredin conjunction with the following drawings, in which:

FIG. 1 illustrates an exemplary (and simplified) wireless communicationsystem, according to some embodiments;

FIG. 2 illustrates a base station (BS) in communication with a userequipment (UE) device, according to some embodiments;

FIG. 3 illustrates an exemplary (and simplified) cellular networkarchitecture, according to some embodiments;

FIG. 4 illustrates an exemplary block diagram of a UE, according to someembodiments;

FIG. 5 illustrates an exemplary block diagram of a BS, according to someembodiments;

FIG. 6 illustrates an exemplary block diagram of an MME, according tosome embodiments;

FIG. 7 is a communication flow diagram illustrating an exemplary methodfor efficiently releasing RRC connections between wireless devices andbase stations, according to some embodiments;

FIG. 8 is a communication flow diagram illustrating an exemplary methodfor efficient sparse uplink resource usage, according to someembodiments;

FIG. 9 illustrates exemplary events and phases of communication betweena wireless device and a network, according to some embodiments; and

FIG. 10 is a table illustrating examples of possible scheduling requestconfiguration options, according to some embodiments.

While the features described herein may be susceptible to variousmodifications and alternative forms, specific embodiments thereof areshown by way of example in the drawings and are herein described indetail. It should be understood, however, that the drawings and detaileddescription thereto are not intended to be limiting to the particularform disclosed, but on the contrary, the intention is to cover allmodifications, equivalents and alternatives falling within the spiritand scope of the subject matter as defined by the appended claims.

DETAILED DESCRIPTION Acronyms

The following acronyms are used in the present disclosure.

3GPP: Third Generation Partnership Project

3GPP2: Third Generation Partnership Project 2

GSM: Global System for Mobile Communications

GERAN: GSM EDGE Radio Access Network

UMTS: Universal Mobile Telecommunications System

UTRAN: UMTS Terrestrial Radio Access Network or Universal TerrestrialRadio Access Network

LTE: Long Term Evolution

RAN: Radio Access Network

E-UTRAN: Evolved UMTS Radio Access Network or Evolved Universal RadioAccess Network

EPC: Evolved Packet Core

EPS: Evolved Packet Service

MME: Mobility Management Entity

HSS: Home Subscriber Server

AS: Access Stratum

NAS: Non-Access Stratum

RLC: Radio Link Control

RRC: Radio Resource Control

MAC: Media Access Control

IE: Information Element

NW: Network

Terms

The following is a glossary of terms used in this disclosure:

Memory Medium—Any of various types of non-transitory memory devices orstorage devices. The term “memory medium” is intended to include aninstallation medium, e.g., a CD-ROM, floppy disks, or tape device; acomputer system memory or random access memory such as DRAM, DDR RAM,SRAM, EDO RAM, Rambus RAM, etc.; a non-volatile memory such as a Flash,magnetic media, e.g., a hard drive, or optical storage; registers, orother similar types of memory elements, etc. The memory medium mayinclude other types of non-transitory memory as well or combinationsthereof. In addition, the memory medium may be located in a firstcomputer system in which the programs are executed, or may be located ina second different computer system which connects to the first computersystem over a network, such as the Internet. In the latter instance, thesecond computer system may provide program instructions to the firstcomputer for execution. The term “memory medium” may include two or morememory mediums which may reside in different locations, e.g., indifferent computer systems that are connected over a network. The memorymedium may store program instructions (e.g., embodied as computerprograms) that may be executed by one or more processors.

Carrier Medium—a memory medium as described above, as well as a physicaltransmission medium, such as a bus, network, and/or other physicaltransmission medium that conveys signals such as electrical,electromagnetic, or digital signals.

Programmable Hardware Element—includes various hardware devicescomprising multiple programmable function blocks connected via aprogrammable interconnect. Examples include FPGAs (Field ProgrammableGate Arrays), PLDs (Programmable Logic Devices), FPOAs (FieldProgrammable Object Arrays), and CPLDs (Complex PLDs). The programmablefunction blocks may range from fine grained (combinatorial logic or lookup tables) to coarse grained (arithmetic logic units or processorcores). A programmable hardware element may also be referred to as“reconfigurable logic”.

Computer System—any of various types of computing or processing systems,including a personal computer system (PC), mainframe computer system,workstation, network appliance, Internet appliance, personal digitalassistant (PDA), television system, grid computing system, or otherdevice or combinations of devices. In general, the term “computersystem” can be broadly defined to encompass any device (or combinationof devices) having at least one processor that executes instructionsfrom a memory medium.

User Equipment (UE) (or “UE Device”)—any of various types of computersystems devices which are mobile or portable and which performs wirelesscommunications. Examples of UE devices include mobile telephones orsmart phones (e.g., iPhone™, Android™-based phones), portable gamingdevices (e.g., Nintendo DS™, PlayStation Portable™, Gameboy Advance™,iPhone™), wearable devices (e.g., smart watch, smart glasses), laptops,PDAs, portable Internet devices, music players, data storage devices, orother handheld devices, etc. In general, the term “UE” or “UE device”can be broadly defined to encompass any electronic, computing, and/ortelecommunications device (or combination of devices) which is easilytransported by a user and capable of wireless communication.

Wireless Device—any of various types of computer system devices whichperforms wireless communications. A wireless device can be portable (ormobile) or may be stationary or fixed at a certain location. A UE is anexample of a wireless device.

Communication Device—any of various types of computer systems or devicesthat perform communications, where the communications can be wired orwireless. A communication device can be portable (or mobile) or may bestationary or fixed at a certain location. A wireless device is anexample of a communication device. A UE is another example of acommunication device.

Base Station—The term “Base Station” has the full breadth of itsordinary meaning, and at least includes a wireless communication stationinstalled at a fixed location and used to communicate as part of awireless telephone system or radio system.

Processing Element—refers to various elements or combinations ofelements. Processing elements include, for example, circuits such as anASIC (Application Specific Integrated Circuit), portions or circuits ofindividual processor cores, entire processor cores, individualprocessors, programmable hardware devices such as a field programmablegate array (FPGA), and/or larger portions of systems that includemultiple processors.

Channel—a medium used to convey information from a sender (transmitter)to a receiver. It should be noted that since characteristics of the term“channel” may differ according to different wireless protocols, the term“channel” as used herein may be considered as being used in a mannerthat is consistent with the standard of the type of device withreference to which the term is used. In some standards, channel widthsmay be variable (e.g., depending on device capability, band conditions,etc.). For example, LTE may support scalable channel bandwidths from 1.4MHz to 20 MHz. In contrast, WLAN channels may be 22 MHz wide whileBluetooth channels may be 1 Mhz wide. Other protocols and standards mayinclude different definitions of channels. Furthermore, some standardsmay define and use multiple types of channels, e.g., different channelsfor uplink or downlink and/or different channels for different uses suchas data, control information, etc.

Band—The term “band” has the full breadth of its ordinary meaning, andat least includes a section of spectrum (e.g., radio frequency spectrum)in which channels are used or set aside for the same purpose.

Automatically—refers to an action or operation performed by a computersystem (e.g., software executed by the computer system) or device (e.g.,circuitry, programmable hardware elements, ASICs, etc.), without userinput directly specifying or performing the action or operation. Thusthe term “automatically” is in contrast to an operation being manuallyperformed or specified by the user, where the user provides input todirectly perform the operation. An automatic procedure may be initiatedby input provided by the user, but the subsequent actions that areperformed “automatically” are not specified by the user, i.e., are notperformed “manually”, where the user specifies each action to perform.For example, a user filling out an electronic form by selecting eachfield and providing input specifying information (e.g., by typinginformation, selecting check boxes, radio selections, etc.) is fillingout the form manually, even though the computer system must update theform in response to the user actions. The form may be automaticallyfilled out by the computer system where the computer system (e.g.,software executing on the computer system) analyzes the fields of theform and fills in the form without any user input specifying the answersto the fields. As indicated above, the user may invoke the automaticfilling of the form, but is not involved in the actual filling of theform (e.g., the user is not manually specifying answers to fields butrather they are being automatically completed). The presentspecification provides various examples of operations beingautomatically performed in response to actions the user has taken.

FIGS. 1-3—Communication System

FIG. 1 illustrates an exemplary (and simplified) wireless communicationsystem in which aspects of this disclosure may be implemented, accordingto some embodiments. For example, any or all of the wireless devicesillustrated in FIG. 1 may be configured for efficient sparse networkusage and/or connection release, e.g., according to the methods of FIGS.7-8. It is noted that the system of FIG. 1 is merely one example of apossible system, and embodiments may be implemented in any of varioussystems, as desired.

As shown, the exemplary wireless communication system includes a basestation 102A which communicates over a transmission medium with one ormore user devices 106A, 106B, etc., through 106N. Each of the userdevices may be referred to herein as a “user equipment” (UE). Thus, theuser devices 106 are referred to as UEs or UE devices.

The base station 102A may be a base transceiver station (BTS) or cellsite, and may include hardware and/or software that enables wirelesscommunication with the UEs 106A through 106N. The base station 102A mayalso be equipped to communicate with a network 100 (e.g., a core networkof a cellular service provider, a telecommunication network such as apublic switched telephone network (PSTN), and/or the Internet, amongvarious possibilities). Thus, the base station 102A may facilitatecommunication among the user devices and/or between the user devices andthe network 100.

The communication area (or coverage area) of the base station may bereferred to as a “cell.” The base station 102A and the UEs 106 may beconfigured to communicate over the transmission medium using any ofvarious radio access technologies (RATs), also referred to as wirelesscommunication technologies, or telecommunication standards, such as GSM,UMTS (WCDMA, TD-SCDMA), LTE, LTE-Advanced (LTE-A), 3GPP2 CDMA2000 (e.g.,1×RTT, NEV-DO, HRPD, eHRPD), Wi-Fi, WiMAX etc.

Base station 102A and other similar base stations (such as base stations102B . . . 102N) operating according to the same or a different cellularcommunication standard may thus be provided as a network of cells, whichmay provide continuous or nearly continuous overlapping service to UEs106A-N and similar devices over a geographic area via one or morecellular communication standards.

Thus, while base station 102A may act as a “serving cell” for UEs 106A-Nas illustrated in FIG. 1, each UE 106 may also be capable of receivingsignals from (and possibly within communication range of) one or moreother cells (which might be provided by base stations 102B-N and/or anyother base stations), which may be referred to as “neighboring cells”.Such cells may also be capable of facilitating communication betweenuser devices and/or between user devices and the network 100. Such cellsmay include “macro” cells, “micro” cells, “pico” cells, and/or cellswhich provide any of various other granularities of service area size.For example, base stations 102A-B illustrated in FIG. 1 might be macrocells, while base station 102N might be a micro cell. Otherconfigurations are also possible.

Note that a UE 106 may be capable of communicating using multiplewireless communication standards. For example, a UE 106 might beconfigured to communicate using two or more of GSM, UMTS, CDMA2000,WiMAX, LTE, LTE-A, WLAN, Bluetooth, one or more global navigationalsatellite systems (GNSS, e.g., GPS or GLONASS), one and/or more mobiletelevision broadcasting standards (e.g., ATSC-M/H or DVB-H), etc. Othercombinations of wireless communication standards (including more thantwo wireless communication standards) are also possible.

FIG. 2 illustrates user equipment 106 (e.g., one of the devices 106Athrough 106N) in communication with a base station 102 (e.g., one of thebase stations 102A through 102N), according to some embodiments. The UE106 may be a device with cellular communication capability such as amobile phone, a hand-held device, a wearable device, a computer or atablet, or virtually any type of wireless device.

The UE 106 may include a processor that is configured to execute programinstructions stored in memory. The UE 106 may perform any of the methodembodiments described herein by executing such stored instructions.Alternatively, or in addition, the UE 106 may include a programmablehardware element such as an FPGA (field-programmable gate array) that isconfigured to perform any of the method embodiments described herein, orany portion of any of the method embodiments described herein.

As noted above, the UE 106 may be configured to communicate using any ofmultiple RATs. For example, the UE 106 may be configured to communicateusing two or more of GSM, CDMA2000, LTE, LTE-A, WLAN, or GNSS. Othercombinations of wireless communication technologies are also possible.

The UE 106 may include one or more antennas for communicating using oneor more wireless communication protocols or technologies. In oneembodiment, the UE 106 might be configured to communicate using eitherof CDMA2000 (1×RTT/1×EV-DO/HRPD/eHRPD) or LTE using a single sharedradio and/or GSM or LTE using the single shared radio. The shared radiomay couple to a single antenna, or may couple to multiple antennas(e.g., for MIMO) for performing wireless communications. In general, aradio may include any combination of a baseband processor, analog RFsignal processing circuitry (e.g., including filters, mixers,oscillators, amplifiers, etc.), or digital processing circuitry (e.g.,for digital modulation as well as other digital processing). Similarly,the radio may implement one or more receive and transmit chains usingthe aforementioned hardware. For example, the UE 106 may share one ormore parts of a receive and/or transmit chain between multiple wirelesscommunication technologies, such as those discussed above.

In some embodiments, the UE 106 may include separate transmit and/orreceive chains (e.g., including separate RF and/or digital radiocomponents) for each wireless communication protocol with which it isconfigured to communicate. As a further possibility, the UE 106 mayinclude one or more radios which are shared between multiple wirelesscommunication protocols, and one or more radios which are usedexclusively by a single wireless communication protocol. For example,the UE 106 might include a shared radio for communicating using eitherof LTE or 1×RTT (or LTE or GSM), and separate radios for communicatingusing each of Wi-Fi and Bluetooth. Other configurations are alsopossible.

FIG. 3 illustrates an exemplary, simplified portion of a wirelesscommunication system in which aspects of this disclosure, includingtechniques for efficient sparse network usage and/or connection releasesuch as according to the methods of FIGS. 7-8, may be implemented. Thewireless communication system of FIG. 3 may be illustrative of a portionof a 3GPP compliant cellular network, according to some embodiments.

As shown, a UE 106 may be in communication with a base station, shown inthis exemplary embodiment as an eNodeB 102. In turn, the eNodeB may becoupled to a core network, shown in this exemplary embodiment as anevolved packet core (EPC) 100. As shown, the EPC 100 may includemobility management entity (MME) 322, home subscriber server (HSS) 324,and serving gateway (SGW) 326. The EPC 100 may include various otherdevices and/or entities known to those skilled in the art as well.

FIG. 4—Exemplary Block Diagram of a UE

FIG. 4 illustrates an exemplary block diagram of a UE 106, according tosome embodiments. As shown, the UE 106 may include a system on chip(SOC) 400, which may include portions for various purposes. For example,as shown, the SOC 400 may include processor(s) 402 which may executeprogram instructions for the UE 106 and display circuitry 404 which mayperform graphics processing and provide display signals to the display460. The processor(s) 402 may also be coupled to memory management unit(MMU) 440, which may be configured to receive addresses from theprocessor(s) 402 and translate those addresses to locations in memory(e.g., memory 406, read only memory (ROM) 450, NAND flash memory 410)and/or to other circuits or devices, such as the display circuitry 404,wireless communication circuitry 430, connector I/F 420, and/or display460. The MMU 440 may be configured to perform memory protection and pagetable translation or set up. In some embodiments, the MMU 440 may beincluded as a portion of the processor(s) 402.

As also shown, the SOC 400 may be coupled to various other circuits ofthe UE 106. For example, the UE 106 may include various types of memory(e.g., including NAND flash 410), a connector interface 420 (e.g., forcoupling to a computer system, dock, charging station, etc.), thedisplay 460, and wireless communication circuitry 430 (e.g., for LTE,CDMA2000, Bluetooth, Wi-Fi, etc.).

As noted above, the UE 106 may be configured to communicate wirelesslyusing multiple wireless communication technologies. As further notedabove, in such instances, the wireless communication circuitry 430 mayinclude radio components that are shared between multiple wirelesscommunication technologies and/or radio components that are configuredexclusively for use according to a single wireless communicationtechnology. As shown, the UE device 106 may include at least one antenna(and possibly multiple antennas, e.g., for MIMO and/or for implementingdifferent wireless communication technologies, among variouspossibilities), for performing wireless communication with cellular basestations and/or other devices. For example, the UE device 106 may useantenna(s) 435 to perform the wireless communication.

As described further subsequently herein, the UE 106 may includehardware and software components for implementing part or all of themethods described herein. The processor 402 of the UE device 106 may beconfigured to implement part or all of the features described herein,e.g., by executing program instructions stored on a memory medium (e.g.,a non-transitory computer-readable memory medium). Alternatively (or inaddition), processor 402 may be configured as a programmable hardwareelement, such as an FPGA (Field Programmable Gate Array), or as an ASIC(Application Specific Integrated Circuit). Alternatively (or inaddition) the processor 402 of the UE device 106, in conjunction withone or more of the other components 400, 404, 406, 410, 420, 430, 435,440, 450, 460 may be configured to implement part or all of the featuresdescribed herein.

FIG. 5—Base Station

FIG. 5 illustrates an exemplary block diagram of a base station 102,according to some embodiments. It is noted that the base station of FIG.5 is merely one example of a possible base station. As shown, the basestation 102 may include processor(s) 504 which may execute programinstructions for the base station 102. The processor(s) 504 may also becoupled to memory management unit (MMU) 540, which may be configured toreceive addresses from the processor(s) 504 and translate thoseaddresses to locations in memory (e.g., memory 560 and read only memory(ROM) 550) or to other circuits or devices.

The base station 102 may include at least one network port 570. Thenetwork port 570 may be configured to couple to a telephone network andprovide a plurality of devices, such as UE devices 106, access to thetelephone network as described above.

The network port 570 (or an additional network port) may also oralternatively be configured to couple to a cellular network, e.g., acore network of a cellular service provider. The core network mayprovide mobility related services and/or other services to a pluralityof devices, such as UE devices 106. In some cases, the network port 570may couple to a telephone network via the core network, and/or the corenetwork may provide a telephone network (e.g., among other UE devicesserviced by the cellular service provider).

The base station 102 may include at least one antenna 534, and possiblymultiple antennas. The antenna(s) 534 may be configured to operate as awireless transceiver and may be further configured to communicate withUE devices 106 via radio 530. The antenna(s) 534 communicates with theradio 530 via communication chain 532. Communication chain 532 may be areceive chain, a transmit chain or both. The radio 530 may be configuredto communicate via various wireless communication technologies,including, but not limited to, LTE, LTE-A, GSM, WCDMA, CDMA2000, Wi-Fi,etc.

The processor(s) 504 of the base station 102 may be configured toimplement part or all of the methods described herein, e.g., byexecuting program instructions stored on a memory medium (e.g., anon-transitory computer-readable memory medium). Alternatively, theprocessor 504 may be configured as a programmable hardware element, suchas an FPGA (Field Programmable Gate Array), or as an ASIC (ApplicationSpecific Integrated Circuit), or a combination thereof.

FIG. 6—Mobility Management Entity

FIG. 6 illustrates an exemplary block diagram of a mobility managemententity (MME) 322, according to some embodiments. It is noted that theMME 322 of FIG. 6 is merely one example of a possible MME 322. As shown,the MME 322 may include processor(s) 604 which may execute programinstructions for the MME 322. The processor(s) 604 may also be coupledto memory management unit (MMU) 640, which may be configured to receiveaddresses from the processor(s) 604 and translate those addresses tolocations in memory (e.g., memory 660 and read only memory (ROM) 650) orto other circuits or devices.

The MME 322 may include at least one network port 670. The network port670 may be configured to couple to one or more base stations and/orother cellular core network entities and/or devices.

The MME 322 may provide mobility related services to a plurality ofdevices, such as UE devices 106. For example, the MME 322 may beresponsible for registering UE devices which attempt to perform anattach procedure, a tracking area update procedure, and/or any ofvarious other procedures.

The MME 322 may communicate with base stations (e.g., eNBs) and/or othercore network entities/devices by means of any of various communicationprotocols and/or interfaces. As one example, in a 3GPP context, the MME322 may use any of an S1-MME, S3, S10, S11, S6a, and/or any of variousother communication protocols or interfaces to communicate with othercellular network components.

The processor(s) 604 of the MME 322 may be configured to implement partor all of the methods described herein, e.g., by executing programinstructions stored on a memory medium (e.g., a non-transitorycomputer-readable memory medium). Alternatively, the processor 604 maybe configured as a programmable hardware element, such as an FPGA (FieldProgrammable Gate Array), or as an ASIC (Application Specific IntegratedCircuit), or a combination thereof.

FIG. 7—Efficient Connection Release

In LTE, a UE may be able to operate in one of the two modes, an idlemode and a connected mode. In the idle mode, Discontinuous Reception(DRX) allows the UE to switch off its radio receiver and thereby reduceits power consumption. At least in some embodiments, it may be the casethat a UE enters the idle mode upon receiving a Radio Resource Control(RRC) connection release message from the network. In the connected modea UE can be in active data transmission or in a connected DRX mode. Theconnected mode DRX pattern may, for example, be used by the UE ifconfigured by the network, and may follow a defined pattern of on andoff cycles. DRX can be configured using any of a variety of settings,and at least in some instances multiple DRX modes (e.g., a short DRX ora long DRX) may be configured as desired.

At least in some instances, a UE may be in an out-of-sync state when thenetwork tries (e.g., as a result of an inactivity timer expiring) torelease the RRC connection of the UE. In such a case, the UE might beexpected to regain synchronization with its serving base station just toreceive the RRC connection release message and respond with a L2acknowledgement to the RRC connection release message. This mayrepresent a substantial amount of power consumption. Accordingly, moreefficient techniques for releasing RRC connections could potentiallyreduce the power consumption of wireless devices.

FIG. 7 is a communication/signal flow diagram illustrating one suchscheme for efficiently releasing RRC connections between wirelessdevices and base stations, according to some embodiments. The schemeshown in FIG. 7 may be used in conjunction with any of the computersystems or devices shown in the above Figures, among other devices. Invarious embodiments, some of the elements of the scheme shown may beperformed concurrently, in a different order than shown, or may beomitted. Additional elements may also be performed as desired. As shown,the scheme may operate as follows.

In 702, a UE 106 and a BS 102 may establish an RRC connection. This maybe scheduled in advance or unscheduled. The UE 106 may perform a randomaccess channel (RACH) procedure in order to establish the RRCconnection. Alternatively, the BS 102 may page the UE 106 at a scheduledtime, and the UE 106 may respond to the paging message and exchange RRCconnection establishment parameters with the BS 102 to establish thescheduled RRC connection.

Certain configuration information may be exchanged as part of the RRCconnection establishment procedure, at least in some embodiments. Suchinformation may include timing alignment information, connection releaseprocedures and/or parameters, and/or any of various other types ofinformation.

In 704, the BS 102 may initiate a RRC connection release timer. Theconnection release timer may be used by the BS 102 to determine when torelease the RRC connection with the UE 106.

In 706, the UE 106 may also initiate a RRC connection release timer. Theconnection release timer at the UE 106 may be used by the UE 106 todetermine when to release the RRC connection with the BS 102.

The RRC connection release timers may by synchronized such that theconnection release timer of the UE 106 and the connection release timerof the BS 102 expire at the same time. This may be achieved by way ofdynamically exchanged configuration information (e.g., on a per-RRCconnection basis), or according to a static configuration (e.g.,according to standards documents and/or mutual agreement between devicemakers and infrastructure vendors), as desired. As examples ofparameters that may be used to synchronize the connection releasetimers, each of the UE 106 and the BS 102 may have synchronized baselengths and may re-set or re-start the connection release timer uponcertain events (e.g., data communication events) occurring in asynchronized manner.

In 708 and 710, the BS 102 and the UE 106 may each respectivelydetermine that its connection release timer has expired. Since theconnection release timers may be synchronized, these determinations maybe made simultaneously or approximately simultaneously (e.g., during thesame subframe).

In 712, the BS 102 may release the RRC connection with the UE 106 basedon determining that the RRC connection release timer has expired.

In 714, the UE 106 may initiate a guard timer based on determining thatthe RRC connection release timer has expired. The UE 106 may delayreleasing the RRC connection until after the BS 102 has released the RRCconnection by way of the guard timer, for example in order to avoid raceconditions.

In 716, the UE 106 may determine that the guard timer has expired, andin 718, based on determining that the guard timer has expired, the UE106 may also release the RRC connection.

Since the UE 106 and the BS 102 may each independently (though in asynchronized manner) track when to release the RRC connection, this mayobviate the need for explicit RRC connection release messages andacknowledgements between the UE 106 and the BS 102, at least in someinstances. This may be particularly useful if the UE 106 is in anout-of-sync state (e.g., has an expired timing alignment timer) when theRRC connection is released, since in such a circumstance, the UE 106might be required to perform two RACH procedures in short order (e.g.,to obtain timing alignment and to transmit the acknowledgement) in orderto be able to provide a radio link control (RLC) level acknowledgementto an RRC connection release message.

Alternatively, the UE 106 and the BS 102 may utilize one or more othertechniques for enabling implicit (or partially implicit) RRC connectionrelease between a UE 106 and a BS 102, and/or for reducing the RACHprocedure burden on the UE 106 to complete a RRC connection release whenin an out-of-sync state. For example, consider the followingpossibilities, in which (at least according to some embodiments) the UE106 may not utilize a RRC connection release timer.

As one example, the BS 102 may provide an indication to release an RRCconnection to the UE 106 by way of a paging message. At least in someembodiments, in this case the UE 106 and the BS 102 may each release theRRC connection without any further message exchange, e.g., including RLCor hybrid automatic repeat request (HARQ) acknowledgements.

Note that in such a case the UE 106 may be identified by its cell radionetwork temporary identifier (C-RNTI) or system architecture evolution(SAE) temporary mobile subscriber identifier (S-TMSI) with the pagingcause set to connection release. Note also that this technique may alsoallow a BS 102 to release multiple UEs RRC connections at the same time,at least in some embodiments.

As another example, the BS 102 may provide a RRC connection releasemessage to the UE 106 upon expiration of the RRC connection releasetimer at the BS 102. At least in some embodiments, in this case the UE106 and the BS 102 may each release the RRC connection without anyfurther message exchange, e.g., including RLC or HARQ acknowledgements.

As yet another example, if the UE 106 is out-of-sync with the BS 102,the BS 102 may indicate to the UE 106 to perform a RACH procedure (e.g.,to gain timing alignment), for example by way of a PDCCH order. Such aRACH procedure may be contention-based or contention-free. Once the UE106 is in-sync (e.g., as a result of the RACH), the base station 102 mayprovide a RRC connection release message and provide an uplink grant(e.g., associated with the RRC connection release message) at an offsetfrom the RRC connection release message. The UE 106 may use this uplinkgrant to provide a RLC acknowledgement message (e.g., instead ofperforming a RACH procedure again for receiving an uplink grant withwhich to provide the RLC acknowledgement message) in response to the RRCconnection release message.

As a further example, if the UE 106 is out-of-sync with the BS 102, theBS 102 may indicate to the UE 106 to perform a RACH procedure (e.g., togain timing alignment), for example by way of a PDCCH order. Such a RACHprocedure may be contention-based or contention-free. Once the UE 106 isin-sync (e.g., as a result of the RACH), the base station 102 mayprovide a RRC connection release message and provide scheduling request(SR) resources (e.g., obviating the need for the UE 106 to performanother RACH procedure). The UE 106 may use these SR resources torequest an uplink grant. The BS 102 may provide the requested uplinkgrant, which the UE 106 may use to provide a RLC acknowledgement messagein response to the RRC connection release message.

As a still further example, if the UE 106 is out-of-sync with the BS102, the BS 102 may indicate to the UE 106 to perform a RACH procedure(e.g., to gain timing alignment), for example by way of a PDCCH order.Such a RACH procedure may be contention-based or contention-free. Oncethe UE 106 is in-sync (e.g., as a result of the RACH), the base station102 may provide a RRC connection release message. The UE 106 may respondto the RRC connection release message with an uplink hybrid automaticrepeat request (HARQ) acknowledgement message. Based on the HARQacknowledgement, the BS 102 may be able to determine (e.g., by passinginformation up to the RLC layer) that the UE 106 has received the RRCconnection release message, and each side may complete the RRCconnection release procedure without the UE 106 providing a RLC layeracknowledgement to the BS 102.

As another example, if the UE 106 is out-of-sync with the BS 102, the BS102 may provide a RRC connection release message, and may providesounding reference signal (SRS) resources to the UE 106. The UE 106 maytransmit SRS using the SRS resources, based on which the BS 102 may beable to determine a timing adjustment for the UE 106. The BS 102 mayprovide a timing alignment command (TAC) to the UE 106 including atiming alignment value (e.g., the determined timing adjustment). The BS102 may further provide an uplink grant, which the UE 106 may use toprovide a RLC acknowledgement message in response to the RRC connectionrelease message.

Note that such techniques may be used in association with certainfeatures or groups of features, or may be implemented more generally, asdesired. For example, any of the above-described techniques forefficient RRC connection release may be used (e.g., activated) inconjunction with a feature or group of features associated with thecellular network being aware of one or more active applications and/ortypes of active applications of the UE device, e.g., an ‘applicationaware’ configuration.

FIG. 8—Efficient Sparse Network Resource Usage

There are many communication scenarios in which a wireless device mayperform wireless communication regularly but relatively infrequently.For example, periodic communication of measurement data by a measurementdevice (or a communication device coupled to a measurement device) mightoccur regularly but relatively infrequently. Other application types andcommunication types may also utilize network resources sparsely.Commonly, devices performing such types of communication may also berelatively low power and/or low complexity devices, for which efficientoperation may be of particular importance. Accordingly, techniques forimproving the efficiency of network communication that occurs relativelyinfrequently may be desirable at least for such devices, at leastaccording to some embodiments.

FIG. 8 is a communication/signal flow diagram illustrating one suchscheme for efficient sparse uplink resource usage by a wireless devicein communication with a base station of a cellular network, according tosome embodiments. The scheme shown in FIG. 8 may be used in conjunctionwith any of the computer systems or devices shown in the above Figures,among other devices. In various embodiments, some of the elements of thescheme shown may be performed concurrently, in a different order thanshown, or may be omitted. Additional elements may also be performed asdesired. As shown, the scheme may operate as follows.

In 802, a UE 106 and a BS 102 may establish an RRC connection. This maybe scheduled in advance or unscheduled. The UE 106 may perform a randomaccess (RACH) procedure in order to establish the RRC connection.Alternatively, the BS 102 may page the UE 106 at a scheduled time, andthe UE 106 may respond to the paging message and exchange RRC connectionestablishment parameters with the BS 102 to establish the scheduled RRCconnection.

Certain configuration information may be exchanged as part of the RRCconnection establishment procedure, at least in some embodiments. Suchinformation may include timing alignment information, connection releaseprocedures and/or parameters, and/or any of various other types ofinformation. Thus, the UE 106 may receive initial timing alignmentinformation during the RRC connection establishment procedure. The UE106 may also receive timing alignment information from the BS 102 atother times, e.g., according to a periodic schedule while in an RRCconnected state.

In 804, the UE 106 may determine that a timing alignment timer of the UE106 has expired. This may occur, in some instances, if a radio linkbetween the UE 106 and the BS 102 is poor. As another possibility, thismay occur if the BS 102 has stopped sending timing alignment commands,for example because the UE 106 is communicating with the BS 102infrequently.

In 806, the UE 106 may determine a mobility state of the UE device. Forexample, the UE 106 may determine whether the UE 106 is ‘mobile’ or‘stationary’. Other mobility states (e.g., ‘semi-stationary’,‘semi-mobile’, etc.) are also possible. The mobility state of the UE 106may be determined based on any of various mobility indicators, includingradio condition based indicators (e.g., using signal strength, signalquality, and/or other metrics relating to the serving base station,neighboring base stations, etc.), internal device based indicators(e.g., using motion detection device circuitry, such as gyroscope(s),accelerometer(s), and/or other sensing components), etc. Note that themobility state of the UE 106 may be associated with any of various timewindows. For example, the mobility state of the UE 106 may be aninstantaneous mobility state based on current conditions. As anotherpossibility, the mobility state may be based on (average, total, orother measure of) an amount of motion over a period of time, such as aperiod of time since a timing alignment command was most recentlyreceived.

In some embodiments, if the UE 106 is in a first mobility state (e.g.,associated with stationary or semi-stationary status), the UE 106 maydetermine that it can continue to use the most recent timing alignmentinformation for uplink communications even after the timing alignmenttimer has expired. If the UE 106 is in a second mobility state (e.g.,associated with mobile status), the UE 106 may determine not to continueto use the most recent timing alignment information for uplinkcommunications after the timing alignment timer has expired, and insteadto perform a RACH procedure to regain network timing synchronization iffurther uplink communication is desired after the timing alignment timerhas expired.

In some embodiments, the UE 106 may retain (e.g., instead of releasing)its previously allocated SR resources after the timing alignment timerhas expired. In this case (and possibly depending on the mobility stateof the UE 106), in 808 the UE 106 may use such SR resources to send ascheduling request to the BS 102. For example, the UE 106 may send sucha SR if it has data in its uplink buffer (e.g., in which case the UE 106may have a buffer status report to send). The UE 106 may use previouslyreceived (e.g., most recent) timing alignment information to send theSR.

Since the UE 106 may have been relatively stationary since most recentlyreceiving timing alignment information, the timing alignment of the SRmay be sufficiently accurate that the BS 102 is able to successfullyreceive and decode the SR. Accordingly, in 810, the BS 102 may providean uplink grant to the UE 106 in response to the SR.

In 812, the UE 106 may perform uplink communication using the uplinkgrant provided by the BS 102. The uplink communication may also use thepreviously received timing alignment information.

As another possibility (e.g., instead of or in addition to allowing theUE 106 to retain SR resources after the timing alignment timer expires),the BS 102 may occasionally (e.g., periodically, such as for each C-DRXon-duration) provide uplink grants to the UE 106 after the timingalignment timer expires. This may free the SR/PUCCH resources of thenetwork that were allocated to the UE 106 while still allowing amechanism for the UE 106 to perform uplink communication usingpreviously received timing alignment information after the timingalignment timer expires.

Such techniques may be useful (among various possible scenarios) when aUE 106 sparsely uses network resources. For example, such techniques maybe used in conjunction with relatively long C-DRX cycles (e.g., 640 ms,1.28 s), with minimal SR allocations (e.g., 1 SR per C-DRX cycle, 2 SRsper C-DRX cycle, 1 SR every other C-DRX cycle, or any other desiredallocation). In such cases, a UE 106 may be able to perform occasionalnetwork communication with fewer PUCCH/SR procedures than mightotherwise be required to maintain timing alignment, and/or to avoidexcessive RACH procedures while being connected and transitioningbetween UL In sync phase and Out of Sync Phases.

FIGS. 9-10—Additional Information

FIGS. 9-10 and the additional description provided herein below inconjunction therewith are provided as being illustrative of furtherconsiderations and possible implementation details of the methods ofFIGS. 7-8, and are not intended to be limiting to the disclosure as awhole. Numerous variations and alternatives to the details providedherein below are possible and should be considered within the scope ofthe disclosure.

In certain circumstances, such as (at least according to someembodiments) when operating in conjunction with application awarenetwork features, a device may transition between uplink (UL)out-of-sync (00S) and UL in-sync (INS) while remaining in an RRCconnected state.

While such a device moves between UL OOS and UL INS, its C-DRX cycle maybe modified for power gains (e.g., power consumption reduction). The INSand OOS transition may be controlled by the Timing Alignment Timer(TAT).

Due to INS and OOS transitions, while the inactivity timer in the NW isabout to expire, the UE might be in the OOS state. The NW may try torelease the RRC connection at inactivity timer expiry. To perform thisRRC connection Release, the NW may generally send a RRC ConnectionRelease Request to the UE and the UE may be expected to respond with aL2 (e.g., RLC) ACK for the release request message.

However, if the UE is in the OOS state, NW may not be able to directlysend the message unless it triggers a RACH (e.g., using a PDCCH Order)and the UE transitions back to INS.

Once the UE transitions to the INS state, the UE may trigger one moreRACH, as it may not have the UL resources to send a UL RLC ACK inresponse to the connection release message.

Because of this behavior there can be two RACHs for a connection releasethat happens while the UE is UL OOS. This may result in substantialpower consumption.

FIG. 9 illustrates such a possible network communication sequence inwhich multiple RACHs are used to complete a RRC connection release whenthe UE is in the OOS state.

A variety of alternative RRC connection release arrangements that reduceor eliminate the need to RACH to complete the RRC connection releasewhen the UE is in the OOS state are possible.

A first such arrangement may include an implicit connection release.Using synchronized timers both at NW and UE, both the entities canrelease the connection synchronously, thereby avoiding the two RACHs. Inthis method synchronized timer(s) are maintained at both UE and NW.These timers are started/re-started at every Tx/Rx at both UE and NW. Asthe Tx at UE and Rx at NW and vice versa happen at the same system framenumber (SFN) and sub frame number, the timer(s) at UE and NW will besynchronized.

When the data activity stops these timer(s) run to expiry. At the expiryof the timer(s) both UE and NW will release the connection. In order toavoid any race conditions due to re-transmissions UE will release theconnection later than the NW. The time difference between UE releasingthe connection and NW releasing the connection is maintained by a guardtimer. The synchronized timer(s) and the guard timer used in thisprocess can either be static or negotiated per connection.

Note that this arrangement may be used while a UE is in uplinkout-of-sync phase and/or while a UE is in uplink in-sync phase. Forexample, such an arrangement may reduce the signaling overhead performedbetween a UE and an eNB to release the UE's RRC connection whether theUE is in-sync or out-of-sync, and/or it may be simpler forinfrastructure vendors and/or device vendors to implement such anarrangement such that it is in effect both when a UE is in-sync and whena UE is out-of-sync.

A second such arrangement may include using a paging message to releasethe RRC connection. The UE can be identified by way of its C-RNTI.

As a third such arrangement, instead of sending a PDCCH Order, the NWcan send the RRC connection release message directly. Using this, the UEcan release the connection and not send either a PUCCH ACK or an RLCACK.

As a fourth such arrangement, the UE may perform the first RACH (e.g., acontention free RACH) with a PDCCH order from the NW to transition theUE into UL INS. Once the UE is UL INS, the NW can give an UL grant at anoffset from the point of sending connection release to the UE. The UEmay wait for this UL grant and send the UL RLC ACK when the UL grant isreceived.

As a fifth such arrangement, the UE may perform the first RACH (e.g., acontention free RACH) with a PDCCH order from the NW to transition theUE into UL INS. Once that RACH is successful, along with the connectionrelease message, the NW can reconfigure the SR resources using which theUE will be able to send the UL RLC ACK and complete the procedure.

As a sixth such arrangement, the UE may perform the first RACH (e.g., acontention free RACH) with a PDCCH order from the NW to transition theUE into UL INS. At the completion of the RACH, the NW may be confidentthat the UE is reachable and may send the connection release to UE. Atthe reception of a UL HARQ ACK from the UE, the NW can confirm that theUE has received the connection release and complete the procedure. Inother words, at this stage both the UE and the NW can complete theprocedure instead of UE further sending the UL RLC ACK for connectionrelease message.

As a seventh such arrangement, the NW can send the RRC connectionrelease message directly to the UE instead of triggering a PDCCH orderfor a RACH. Along with the connection release message, the NW can alsoconfigure SRS resources for the UE. The UE can TX SRS using the SRSresources and the NW may be able to determine the timing adjustment forthe UE based on this. Once this timing adjustment is obtained, the NWcan provide a TAC to the UE, and later provide an UL grant for the UE tosend an UL RLC ACK in response to the connection release message.

As another characteristic of the 00S state, it may be the case that a UEreleases all the PUCCH/SR resources. Thus, in this phase, if the UE hasto send any data in UL, it generally has to start by performing a RACHprocedure. As previously noted, RACH procedures may be more costly interms of power consumption than remaining INS, and may also lead to moredelay then being INS when starting uplink data communication.

However, if a UE were to remain in the INS phase even in times of sparseresource usage, this could represent a substantial burden on basestation (e.g., eNB) PUCCH/SR resources, such that there might not besufficient such resources for all the UEs in the network. Accordingly,the following techniques for efficient sparse network resource usagethat take the above considerations into account are proposed.

As one possibility, the UE may be able to remain in the UL INS phasewith long DRX cycles (e.g., 1.28 sec). While being in such a long DRXcycle, SR resources may be sparsely allocated to the UE, such as one SRper DRX cycle.

While current specification documents do not allow the SR resources tobe this sparse (e.g., the max periodicity that is possible according tothe table illustrated as FIG. 10 is 80 ms), specification changes (e.g.,to create one or more new SR configuration indices, such as indices atDRX cycle periodicities such as 640 ms or 1280 ms) or proprietaryimplementations (e.g., such as allowing a base station to configure a UEto use one of the configurations illustrated in FIG. 10 but restrict itto using the resources only in specific SFN, sub frames to effectivelyprovide one SR per DRX cycle) may be used to provide such sparse SRresource allocations.

Additionally, the base station may stop or reduce the frequency ofsending TA update commands to the UE. If the base station decides tostop sending the TA commands, then UE will use the last received TAC forthe next transmission.

As another possibility, the UE may be able to remain in UL OOS phasewith long DRX cycles, and to retain (e.g., at least while being in along DRX cycle) allocated SR resources while in the OOS phase. Theretained SR resources may be sparse (e.g., one per DRX cycle), such aspreviously discussed.

In this case, the base station may not update the TAC in this locationafter the UE enters UL OOS. If there is any data in UL, UE will send aSR using the last received TAC to determine its timing offset. Note thatas the timing offset may change if UE is in mobility, the UE mayrestrict using the last received TAC to scenarios when its mobilitystate is static or semi static, and may perform a RACH procedure (e.g.,to ensure proper timing alignment) otherwise.

A further possibility may occur, in which the UE is either in UL INS orOOS phase and has released any UL resources. In the duration in which ULresources are released, the base station may send an uplink grant to UEoccasionally (e.g., at every OnDuration of the CDRX cycle), e.g., tocheck if there is any data. If there is any data, the UE may respondwith its buffer status report (BSR) using the last received TAC todetermine its timing offset. As previously described, as the timingoffset may change if UE is in mobility, the UE may restrict using thelast received TAC to scenarios when its mobility is static or semistatic, and may perform a RACH procedure otherwise.

Note that the various features described in the present disclosure maybe implemented individually or in any combination, as desired.

In the following further exemplary embodiments are provided.

One set of embodiments may include a method, comprising: by a wirelessuser equipment (UE) device: establishing a radio resource control (RRC)connection with a base station of a cellular network; initiating aconnection release timer for the RRC connection at the UE device;determining that the connection release timer has expired; releasing theRRC connection based on determining that the connection release timerhas expired.

According to some embodiments, releasing the RRC connection does notinclude receiving a RRC connection release message or transmitting anyacknowlegement messages in response to the RRC connection releasemessage.

According to some embodiments, the connection release timer for the RRCconnection at the UE device is synchronized with a connection releasetimer for the RRC connection at the base station.

According to some embodiments, the method further comprises: receivingconfiguration settings for the connection release timer for the RRCconnection from the base station, wherein the connection release timerfor the RRC connection at the UE device operates according to theconfiguration settings received from the base station.

According to some embodiments, the method further comprises: re-startingthe connection release timer at each data communication between the UEdevice and the base station.

According to some embodiments, the base station is also configured torelease the RRC connection based on determining that a connectionrelease timer for the RRC connection at the base station has expired,wherein the UE is configured to release the RRC connection after thebase station releases the RRC connection.

According to some embodiments, the method further comprises: initiatinga guard timer associated with expiration of the connection releasetimer; and releasing the RRC connection after expiration of the guardtimer.

According to some embodiments, initiating a connection release timer forthe RRC connection at the UE device, determining that the connectionrelease timer has expired, and releasing the RRC connection based ondetermining that the connection release timer has expired are performedby the UE device based at least in part on a first feature or group offeatures being enabled.

According to some embodiments, the first feature or group of featuresare associated with the cellular network being aware of one or moreactive applications and/or types of active applications of the UEdevice.

Another set of embodiments may include a method, comprising: by awireless user equipment (UE) device: establishing a radio resourcecontrol (RRC) connection with a base station of a cellular network;receiving a paging message from the base station indicating to releasethe RRC connection; and releasing the RRC connection based on the pagingmessage indicating to release the RRC connection.

Yet another set of embodiments may include a method, comprising: by awireless user equipment (UE) device: establishing a radio resourcecontrol (RRC) connection with a base station of a cellular network;receiving a RRC connection release message from the base stationindicating to release the RRC connection; and releasing the RRCconnection without sending an acknowledgement message in response to theRRC connection release message.

Still another set of embodiments may include a method, comprising: by awireless user equipment (UE) device: establishing a radio resourcecontrol (RRC) connection with a base station of a cellular network;transitioning to an out-of-sync state with respect to the RRC connectionwith the base station; receiving an indication to perform a randomaccess procedure to gain timing synchronization with the base station;receiving a RRC connection release message from the base stationindicating to release the RRC connection; receiving an uplink grantassociated with the RRC connection release message; and transmitting aradio link control (RLC) acknowledgement message in response to the RRCconnection release message using the uplink grant.

A further set of embodiments may include a method, comprising: by awireless user equipment (UE) device: establishing a radio resourcecontrol (RRC) connection with a base station of a cellular network;transitioning to an out-of-sync state with respect to the RRC connectionwith the base station; receiving an indication to perform a randomaccess procedure to gain timing synchronization with the base station;receiving a RRC connection release message from the base stationindicating to release the RRC connection; receiving scheduling requestresources along with the RRC connection release message; transmitting ascheduling request using the scheduling request resources based onreceiving the RRC connection release message; receiving an uplink grantin response to the scheduling request; and transmitting a radio linkcontrol (RLC) acknowledgement message in response to the RRC connectionrelease message using the uplink grant.

According to some embodiments, the random access procedure is acontention free or contention based random access procedure.

A still further set of embodiments may include a method, comprising: bya wireless user equipment (UE) device: establishing a radio resourcecontrol (RRC) connection with a base station of a cellular network;transitioning to an out-of-sync state with respect to the RRC connectionwith the base station; receiving an indication to perform a randomaccess procedure to gain timing synchronization with the base station;receiving a RRC connection release message from the base stationindicating to release the RRC connection; transmitting a hybridautomatic repeat request (HARQ) acknowledgement in response to the RRCconnection release message, and releasing the RRC connection withoutsending a radio link control (RLC) acknowledgement message in responseto the RRC connection release message.

A yet further set of embodiments may include a method, comprising: by awireless user equipment (UE) device: establishing a radio resourcecontrol (RRC) connection with a base station of a cellular network;receiving timing alignment information from the base station;determining that a timing alignment timer has expired; and performing anuplink communication after the timing alignment timer has expired usingpreviously received timing alignment information.

According to some embodiments, the method further comprises: determininga mobility state of the UE device; wherein the UE device is configuredto perform the uplink communication after the timing alignment timer hasexpired using previously received timing alignment information if the UEdevice is in a first mobility state associated with stationary orsemi-stationary status, wherein the UE device is configured to perform arandom access procedure to obtain timing alignment prior to performinguplink communication after the timing alignment timer has expired if theUE device is in a second mobility state associated with mobile status.

According to some embodiments, the method further comprises: retainingscheduling request (SR) resources after the timing alignment timer hasexpired; and using the SR resources retained after the timing alignmenttimer has expired to perform the uplink communication.

According to some embodiments, the method further comprises: receivingan uplink grant from the base station during a connected modediscontinuous reception (C-DRX) on-duration after the timing alignmenttimer has expired; using the uplink grant to perform the uplinkcommunication after the timing alignment timer has expired using thepreviously received timing alignment information.

Another set of embodiments may include a wireless user equipment (UE)device, comprising: a radio; and a processing element; wherein the radioand the processing element are configured to perform any of the methodsof the preceding examples.

Yet another set of embodiments may include a method, comprising: by abase station (BS): establishing a radio resource control (RRC)connection with a wireless user equipment (UE) device; initiating aconnection release timer for the RRC connection; determining that theconnection release timer has expired; and releasing the RRC connectionbased on determining that the connection release timer has expired.

According to some embodiments, the BS does not transmit a RRC connectionrelease message to the UE device as part of releasing the RRCconnection.

According to some embodiments, the BS indicates to the UE device torelease the RRC connection using a paging message.

According to some embodiments, the BS transmits a RRC connection releasemessage to the UE device as part of releasing the RRC connection,wherein the BS releases the RRC connection even without receiving anacknowledgement message in response to the RRC connection releasemessage.

According to some embodiments, releasing the RRC connection furthercomprises, if the UE device is out-of-sync when the connection releasetimer has expired: indicating to the UE device to perform a randomaccess procedure to gain timing synchronization with the base station;providing a RRC connection release message to the UE device; providingan uplink grant to the UE device based on providing the RRC connectionrelease message to the UE device; and receiving a radio link control(RLC) level acknowledgment to the RRC connection release message fromthe UE device using the uplink grant.

According to some embodiments, releasing the RRC connection furthercomprises, if the UE device is out-of-sync when the connection releasetimer has expired: indicating to the UE device to perform a randomaccess procedure to gain timing synchronization with the base station;providing a RRC connection release message to the UE device; providingscheduling request resources to the UE device based on providing the RRCconnection release message to the UE device; receiving a schedulingrequest from the UE device; providing an uplink grant to the UE devicein response to the scheduling request; and receiving a radio linkcontrol (RLC) level acknowledgment to the RRC connection release messagefrom the UE device using the uplink grant.

According to some embodiments, releasing the RRC connection furthercomprises, if the UE device is out-of-sync when the connection releasetimer has expired: indicating to the UE device to perform a randomaccess procedure to gain timing synchronization with the base station;providing a RRC connection release message to the UE device; receiving ahybrid automatic repeat request (HARQ) acknowledgement to the RRCconnection release message from the UE device; and determining that theUE device has received the RRC connection release message at a radiolink control layer of the base station based on the HARQacknowledgement.

Still another set of embodiments may include a method, comprising: by abase station (BS): establishing a radio resource control (RRC)connection with a wireless user equipment (UE) device; providing timingalignment information to the UE device; determining that a timingalignment timer associated with the UE device has expired; and receivingan uplink communication from the UE device after the timing alignmenttimer has expired.

According to some embodiments, the UE device retains allocatedscheduling request (SR) resources after the timing alignment timerassociated with the UE device has expired, and the method furthercomprises: receiving a SR from the UE device after the timing alignmenttimer associated with the UE device has expired; and providing an uplinkgrant to the UE device after the timing alignment timer associated withthe UE device has expired in response to the SR; wherein the uplinkcommunication is performed using the provided uplink grant.

According to some embodiments, the method further comprises: providingan uplink grant to the UE device during a connected mode discontinuousreception (C-DRX) on-duration after the timing alignment timer hasexpired; wherein the uplink communication is performed using theprovided uplink grant.

A further set of embodiments may include a cellular base station (BS),comprising: a radio; and a processing element; wherein the radio and theprocessing element are configured to perform any of the methods of thepreceding examples.

Another set of embodiments may include a non-transitory computeraccessible memory medium comprising program instructions which, whenexecuted at a device, cause the device to implement any of the methodsof any of the preceding examples.

A still further set of embodiments may include a computer programcomprising instructions for performing any of the methods of any of thepreceding examples.

Yet another set of embodiments may include an apparatus comprising meansfor performing any or all of the method elements of any of the precedingexamples.

A yet further set of embodiments may include an integrated circuitconfigured to perform any of the method elements of any of the precedingexamples

Embodiments of the present disclosure may be realized in any of variousforms. For example some embodiments may be realized as acomputer-implemented method, a computer-readable memory medium, or acomputer system. Other embodiments may be realized using one or morecustom-designed hardware devices such as ASICs. Still other embodimentsmay be realized using one or more programmable hardware elements such asFPGAs.

In some embodiments, a non-transitory computer-readable memory mediummay be configured so that it stores program instructions and/or data,where the program instructions, if executed by a computer system, causethe computer system to perform a method, e.g., any of a methodembodiments described herein, or, any combination of the methodembodiments described herein, or, any subset of any of the methodembodiments described herein, or, any combination of such subsets.

In some embodiments, a device (e.g., a UE 106) may be configured toinclude a processor (or a set of processors) and a memory medium, wherethe memory medium stores program instructions, where the processor isconfigured to read and execute the program instructions from the memorymedium, where the program instructions are executable to implement anyof the various method embodiments described herein (or, any combinationof the method embodiments described herein, or, any subset of any of themethod embodiments described herein, or, any combination of suchsubsets). The device may be realized in any of various forms.

Although the embodiments above have been described in considerabledetail, numerous variations and modifications will become apparent tothose skilled in the art once the above disclosure is fully appreciated.It is intended that the following claims be interpreted to embrace allsuch variations and modifications.

What is claimed is:
 1. An apparatus, comprising: a processing element configured to cause the apparatus to: establish a radio resource control (RRC) connection with a base station of a cellular network; determine to release the RRC connection; and release the RRC connection without sending a radio link control (RLC) layer acknowledgement message indicating that the RRC connection has been released to the base station.
 2. The apparatus of claim 1, wherein the processing element is further configured to cause the apparatus to: receive a RRC connection release message from the base station indicating to release the RRC connection, wherein determining to release the RRC connection is based at least in part on receiving the RRC connection release message from the base station.
 3. The apparatus of claim 1, wherein the processing element is further configured to cause the apparatus to: receive a RRC connection release message from the base station indicating to release the RRC connection; and provide a hybrid automatic repeat request (HARQ) acknowledgement message in response to the RRC connection release message.
 4. The apparatus of claim 1, wherein the processing element is further configured to cause the apparatus to: initiate a connection release timer for the RRC connection at the apparatus; and determine that the connection release timer at the apparatus has expired; wherein determining to release the RRC connection is based at least in part on the connection release timer at the apparatus expiring.
 5. The apparatus of claim 4, wherein the connection release timer for the RRC connection at the apparatus is synchronized with a connection release timer for the RRC connection at the base station.
 6. The apparatus of claim 4, wherein the processing element is further configured to cause the apparatus to: receive connection release timer configuration settings from the base station, wherein the connection release timer for the RRC connection at the apparatus operates according to the configuration settings received from the base station.
 7. The apparatus of claim 4, wherein the processing element is further configured to cause the apparatus to: initiate a guard timer associated with expiration of the connection release timer at the apparatus; wherein the RRC connection is released after expiration of the guard timer.
 8. The apparatus of claim 1, wherein the processing element is further configured to cause the apparatus to: receive a paging message from the base station indicating to release the RRC connection, wherein determining to release the RRC connection is based at least in part on receiving the paging message from the base station.
 9. A method, comprising: by a wireless user equipment (UE) device: establishing a radio resource control (RRC) connection with a base station of a cellular network; initiating a connection release timer for the RRC connection at the UE device; determining that the connection release timer has expired; and releasing the RRC connection based on determining that the connection release timer has expired.
 10. The method of claim 9, wherein releasing the RRC connection does not include receiving a RRC connection release message or transmitting any acknowlegement messages in response to the RRC connection release message.
 11. The method of claim 9, wherein the connection release timer for the RRC connection at the UE device is synchronized with a connection release timer for the RRC connection at the base station.
 12. The method of claim 9, the method further comprising: receiving configuration settings for the connection release timer for the RRC connection from the base station, wherein the connection release timer for the RRC connection at the UE device operates according to the configuration settings received from the base station.
 13. The method of claim 9, the method further comprising: re-starting the connection release timer at each data communication between the UE device and the base station.
 14. The method of claim 9, wherein the base station is configured to release the RRC connection based on determining that a connection release timer for the RRC connection at the base station has expired, wherein the UE is configured to release the RRC connection after the base station releases the RRC connection.
 15. The method of claim 9, the method further comprising: initiating a guard timer associated with expiration of the connection release timer; and releasing the RRC connection after expiration of the guard timer.
 16. A wireless user equipment (UE) device, comprising: an antenna; a radio communicatively coupled to the antenna; and a processing element communicatively coupled to the radio; wherein the UE device is configured to: establish a radio resource control (RRC) connection with a base station of a cellular network; receive a RRC connection release message from the base station indicating to release the RRC connection, receive an indication of one or more uplink resources associated with the RRC connection release message; and provide an acknowledgement message to the base station in response to the RRC connection release message using the one or more uplink resources associated with the RRC connection release message.
 17. The UE device of claim 16, wherein the one or more uplink resources comprise an uplink grant associated with the RRC connection release message, wherein the acknowledgement message comprises a radio link control (RLC) acknowledgement message.
 18. The UE device of claim 16, wherein the one or more uplink resources comprise scheduling request resources, wherein the UE device is further configured to: transmit a scheduling request to the base station using the scheduling request resources based on receiving the RRC connection release message; and receive an uplink grant in response to the scheduling request; wherein the acknowledgement message comprises a radio link control (RLC) acknowledgement message, wherein the RLC acknowledgement message is provided to the base station using the uplink grant.
 19. The UE device of claim 16, wherein the UE device is further configured to: transition to an out-of-sync state with respect to the RRC connection with the base station; receive an indication to perform a random access procedure to gain timing synchronization with the base station; and perform the random access procedure to gain timing synchronization with the base station, wherein the RRC connection release message is received once the UE device has gained timing synchronization with the base station.
 20. The UE device of claim 16, wherein the UE device is further configured to: transition to an out-of-sync state with respect to the RRC connection with the base station; receive sounding reference signal resources from the base station, provide SRS to the base station using the SRS resources, and receive a timing alignment command (TAC) from the base station to gain timing synchronization with the base station, wherein the TAC is generated based at least in part on the SRS, wherein the RRC connection release message is received once the UE device has gained timing synchronization with the base station. 